The -s command-line option simplifies the task of creating shortcuts to Photon applications within the Windows desktop.
By using the -s option, you can create an icon or shortcut on the Windows desktop that starts a Photon application automatically (within a private Phindows session). With proper specification of the remote Window manager options, it's possible to make that Photon application look like it's a native Windows application.
When phrelay runs on the QNX host machine, it looks up the Photon service specified with the -s option in a configuration file (/etc/config/phrelay[.node]). If a matching service is found, phrelay launches the specified Photon command instead of the default Photon desktop. You can specify optional Window Manager options, but the default mode is to start the remote Photon application such that it looks and behaves as if it were a native Windows application.
You typically use the -U option along with the -s option to specify a QNX userid to use when running the remote Photon command. If you don't give a userid, and the phrelay service doesn't specify a default one, Photon pops up a login dialog requesting the QNX userid before proceeding. By specifying a userid with the -U option, you can avoid this login dialog.
phindows -tx.x.x.x -svpoker -Ujoe
vpoker % /usr/photon/bin/vpoker
then joe could directly launch a Photon vpoker session (running as QNX userid joe) on his Windows desktop by simply clicking on the icon or shortcut.